1. Field of the Invention
This invention relates to chemistry and, more specifically to novel compounds per se.
2. Description of the Prior Art
In various photographic systems for forming images, whether in black-and-white or in color, it is often desirable to include in the photographic film unit one or more of the various photographic reagents required for development and/or to enhance image quality. This practice extends to both conventional systems for forming negative images and to the various systems such as diffusion transfer, wherein a positive image in silver or in color is obtained.
In many instances, the photographic reagent may be contained initially in either the processing composition applied for development and image formation or in the film unit, the latter being preferred to reduce and hence simplify the number of ingredients required in the processing composition.
In other instances, the particular photographic reagent desired is not sufficiently stable in alkali to provide the requisite shelf life for the processing composition or the reagent is incompatible and/or reactable with another reagent of the composition and hence must be contained initially in the film unit.
In still other instances, the reagent must be provided at some particular time in the development process, which requires that it be contained in a specified layer or in specified proximity to another layer in the film unit.
In all of the foregoing instances it is desirable that the reagent be contained in the desired layer or layers of the particular film unit in such a manner that it is stable, non-migratory or non-diffusible, and yet available when required in the development process.
The present invention is directed to novel compounds which provide advantageous means for incorporating reagents of the above-mentioned type in the photographic product.
The art contains several references to "hydrolyzable" photographic reagent precursors such as, for example, reference in U.S. Pat. No. 3,265,498, issued Aug. 9, 1966 to hydrolyzable development restrainer precursors. However, prior to the present invention, the novel quinone and naphthoquinone-methide precursors of the present invention have been unknown in the art. Our U.S. Pat. No. 3,685,991, issued Aug. 22, 1972 describes integral photographic silver diffusion transfer products and processes employing novel compounds within the scope of this invention.